Allozyme variation in a natural population of Stryphnodendron adstringens in the Rio Preto State Park, southeastern Brazil

Abstract

Leaves and fruits from 63 Stryphnodendron adstringens trees were sampled in the Rio Preto State Park to analyze allozyme segregation, tissue specific expression of allozyme loci, and their genetic parameters. The enzyme systems ADH, EST, ACP, PGM, PGI, GDH, G6PDH, GOT, IDH, LAP, MDH, PER and SKDH were assessed by means of starch-gel electrophoresis. The polymorphic systems PGI, IDH, MDH and GOT demonstrated a dimeric quaternary structure, while EST and PER were monomeric. The total expected genetic diversity (HE) for leaves and seeds were 0.325 and 0.244 respectively. The effective number of alleles per locus (AE) was 1.58 in leaves and 1.42 in seeds. The values of HE and AE observed in S. adstringens were comparatively higher than the average values seen in allozyme studies of other woody plants. The values of the fixation indices for the population, considering leaves (f=0.070) and seeds (f=0.107), were not significant. The high values of genetic diversity and of effective number of alleles per locus, as well as the non-significant fixation index and the adjustments of the Hardy-Weinberg proportions between generations for the pgi-1, mdh-2 and idh-1 loci, indicated random mating in this population. The enzyme systems EST and PER demonstrated their best resolution in leaf tissues, while the MDH, IDH, PGI and GOT systems demonstrated their best resolution in seed tissues.